Frequent Questions

How does the EPA analyze air filters?

RadNet operators ship air filters from the monitoring location to the EPA’s National Analytical Radiation Environmental Laboratory (NAREL) for analysis. All air filters go through an initial screening for beta radiation, followed by a gamma scan if the beta activity is greater than 1 pCi/m3. For each air filter, laboratory analysis provides the average concentration of a contaminant over the sample collection period in picocuries per cubic meter (pCi/m3). RadNet sample analysis on air filters is conducted following a routine schedule, unless analysis is accelerated after an emergency event.

Each year, a composite sample of the air filters for each monitor is analyzed for gamma-emitting radionuclides. Isotopic plutonium (Pu-238, Pu-239/Pu-240) and uranium (U-234, U-235, and U-238) analyses are performed on composite samples from one-fourth of the stations on a four-year rotating schedule. View air filter analysis results for each RadNet air monitoring location on its individual webpage on the RadNet website.